1. Field of the Invention
This invention relates to a cDNA encoding a peroxidase originating from a microorganism (Arthromyces ramosus) and a process for producing the peroxidase by use of host cells containing said gene.
2. Prior Art
In recent years, peroxidases, which are enzymes capable of oxidizing various compounds in the presence of hydrogen peroxide, have been used in the same way as various other oxidases as a clinical diagnostic reagent in assays of glucose, cholesterol, phospholipids, urea and so forth. These enzymes have also been used as a labelled enzyme in enzyme linked immunoassays. They have mainly been produced from plants such as horseradish and Japanese radish. However peroxidases originating from these plants contain isozymes having slightly differing properties from each other, and which therefore require considerable labour costs in order to purify them to such a degree that they are usable as a diagnostic reagent.
On the other hand, some peroxidases of microbial origin have been known. However cytochrome c peroxidases and NADH peroxidases produced by bacteria or fungi are unsuitable as a clinical or diagnostic reagent from the viewpoint of the specificity thereof, since they are generally less specific than the common ones originating from horseradish or Japanese radish. Recently, peroxidases capable of acting on o-dianisidine as a hydrogen donor have been produced from Eschelichia coli or microorganisms belonging to the genus Myrothecium. However this enzyme is also unsuitable for the aforesaid diagnostic use due to the carcinogenic nature of o-dianisidine.
Under these circumstances, the present inventors conducted research to obtain a naturally occurring peroxidase of microbial origin, which is usable as, for example, a clinical diagnostic reagent or a labelled enzyme in enzyme linked immunoassays similar to conventional ones originating from horseradish or Japanese radish. The inventors have already reported a peroxidase produced by a fungus belonging to the genus Arthromyces, which peroxidase has the desired properties (Japanese Patent Laid-Open No. 43987/1986). They further clarified that the peroxidase of the genus Arthromyces is far superior to conventional peroxidases in terms of chemiluminescence generating activity in the case of determining with chemiluminescent reagent, for example, peroxides, as a clinical diagnostic reagent or a labelled enzyme in an enzyme linked immunoassay (refer to Japanese Patent Laid-Open No. 219398/1988).